drm/amdgpu: Track pending retry faults in IH and VM (v2)

IH tracks pending retry faults in a hash table for fast lookup in
interrupt context. Each VM has a short FIFO of pending VM faults for
processing in a bottom half.

The IH prescreening stage adds retry faults and filters out repeated
retry interrupts to minimize the impact of interrupt storms.

It's the VM's responsibility remove pending faults once they are
handled. For now this is only done when the VM is destroyed.

v2:
- Made the hash table smaller and the FIFO longer. I never want the
  FIFO to fill up, because that would make prescreen take longer.
  128 pending page faults should be enough to keep migrations busy.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Christian König <christian.koenig@amd.com> (v1)
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 9b795915cab1..6c1133298b17 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -2680,6 +2680,8 @@ int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
                 vm->pasid = pasid;
         }
 
+        INIT_KFIFO(vm->faults);
+
         return 0;
 
 error_free_root:
@@ -2731,8 +2733,13 @@ void amdgpu_vm_fini(struct amdgpu_device *adev, struct amdgpu_vm *vm)
 {
         struct amdgpu_bo_va_mapping *mapping, *tmp;
         bool prt_fini_needed = !!adev->gart.gart_funcs->set_prt;
+        u64 fault;
         int i;
 
+        /* Clear pending page faults from IH when the VM is destroyed */
+        while (kfifo_get(&vm->faults, &fault))
+                amdgpu_ih_clear_fault(adev, fault);
+
         if (vm->pasid) {
                 unsigned long flags;